BR, your points are well made, but on the subject of form, compare the first class runs made by both players in their last few games (Shield, County, Oz A Tour) if my arithmetic is right:
Wade: 593 runs @ 53
Patterson: 204 @ 18
Labuschagne: 875 @ 58
Marnus is a little unlucky, but he's also been playing Div II county too, so it's a no win situation for the selectors.
Starc is a bit unlucky too, IMHO. He's a top quality one day bowler, but test cricket is different and he has a habit of spraying the ball all over the joint. His record in England is OK, but I think Pattinson is the shock bowler required in these conditions. He has done very well with the Dukes ball and as Mark Waugh says, they'd want the unerring accuracy of Siddle to tie up an end and create pressure. Like he did in the Oval test last time.